Liquid crystal display and method of manufacturing the same

ABSTRACT

A curved liquid crystal display and a method of manufacturing it are presented. The display includes: a substrate having a central portion; a thin film transistor disposed on the substrate; a pixel electrode connected to the thin film transistor; and a roof layer disposed to face the pixel electrode; and a liquid crystal layer disposed between the pixel electrode and the roof layer and formed by a plurality of microcavities, wherein the microcavities hold a liquid crystal material, wherein a difference between a maximum cell gap and a minimum cell gap in each of the microcavities increases with distance from the central portion of the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2014-0149352 filed in the Korean IntellectualProperty Office on Oct. 30, 2014, the entire contents of which areincorporated herein by reference.

BACKGROUND

(a) Field

The present invention relates to a liquid crystal display and amanufacturing method thereof.

(b) Description of the Related Art

Liquid crystal displays are flat panel display devices that are widelyused today. Typically, a liquid crystal display includes two displaypanels—for example field generating electrodes such as a pixel electrodeand a common electrode—with a liquid crystal layer interposedtherebetween.

A liquid crystal display generates an electric field in a liquid crystallayer by applying a voltage to the field generating electrodes tocontrol orientations of liquid crystal molecules in the liquid crystallayer, thereby and polarizing incident light in the desired manner todisplay an image.

A technique of forming a cavity in a pixel and filling the cavity withliquid crystals to implement a display has been developed. Unlike aconventional liquid crystal display that uses two sheets of substrates,this cavity-technique forms constituent elements on one substrate,thereby reducing weight, thickness, and the like of the device.

This cavity-type display device may be applied to a curved panel thathas a curvature. When this panel is bent to have a predeterminedcurvature, a light visibility difference is generated at a centralportion and a peripheral portion.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The present inventive concept has been made in an effort to provide aliquid crystal display, and a manufacturing method thereof, havingadvantages of a cell gap that is gradually changed from a centralportion to a peripheral portion of a panel.

An exemplary embodiment provides a liquid crystal display including: asubstrate having a central portion; a thin film transistor disposed onthe substrate; a pixel electrode connected to the thin film transistor;and a roof layer disposed to face the pixel electrode; and a liquidcrystal layer disposed between the pixel electrode and the roof layerand formed by a plurality of microcavities, wherein the microcavitieshold a liquid crystal material, wherein a difference between a maximumcell gap and a minimum cell gap in each of the microcavities increaseswith distance from the central portion of the substrate.

A pretilt angle of the liquid crystal material disposed at an upperportion of one of the microcavities may be different from that of theliquid crystal material disposed at a lower portion of the same one ofthe microcavities.

A pretilt angle difference between the liquid crystal materials disposedat the upper portion and the lower portion of the microcavities mayincrease from the central portion to the peripheral portion.

The roof layer may have a curved bottom surface that interfaces themicrocavities and a flat top surface that is parallel with thesubstrate.

When the substrate is bent, the bottom surface of the roof layer may beparallel with the substrate and the top surface may have a curvature.

At a microcavity in the peripheral portion, the liquid crystal materialthat is adjacent to the substrate may be substantially verticallyaligned to the substrate and the liquid crystal material that isadjacent to the roof layer may have a tilt angle.

When the substrate is bent, the liquid crystal material that is adjacentto the roof layer may be substantially vertically aligned and the liquidcrystal material that is adjacent to the substrate may have a tilt anglein the microcavities disposed at the peripheral portion.

A difference between a maximum thickness and a minimum thickness of theroof layer increases with distance from the central portion of thesubstrate.

When the substrate is bent, a thickness of the roof layer may beconstant across the substrate.

A forward direction from the central portion to the peripheral portionmay be substantially parallel with long sides of the substrate.

Cell gaps of the microcavities disposed in the central portion of thesubstrate may be substantially constant.

A tilt angle of the liquid crystal material that is adjacent to the rooflayer at the microcavities may increase with distance from the centralportion of the substrate.

An exemplary embodiment of the present invention provides amanufacturing method of a liquid crystal display, including: forming athin film transistor on a substrate; forming a pixel electrode to beconnected to the thin film transistor; forming sacrificial layerpatterns on the pixel electrode; forming a roof layer on the sacrificiallayer patterns; forming a plurality of microcavities by removing thesacrificial layer patterns; forming a liquid crystal layer by injectinga liquid crystal material into the microcavities; and forming a cappinglayer on the roof layer, wherein, in the forming of the sacrificiallayer, a difference between a maximum height and a minimum height ofeach of a plurality of sacrificial layer patterns increases withdistance from a central portion of the substrate.

A slit mask may be used to form the sacrificial layer patterns.

The roof layer may have a curved bottom surface that interfaces themicrocavities and a flat top surface that is parallel with thesubstrate.

The manufacturing method may further include bending the substrate suchthat the bottom surface of the roof layer may be parallel with thesubstrate while the top surface may have a curvature.

A difference between a maximum thickness and a minimum thickness of theroof layer increases with distance from the central portion of thesubstrate.

The manufacturing method may further include bending the substrate suchthat a thickness of the roof layer is constant.

A forward direction from the central portion to the peripheral portionmay be parallel with long sides of the substrate.

Cell gaps of the microcavities disposed at the central portion of thesubstrate based on the long sides of the substrate may be substantiallyconstant.

According to the exemplary embodiments of the present invention, it ispossible to minimize the degree of retardation that is varied accordingto position of panel by designing asymmetric cell gaps in pixel unitssuch that a difference of the asymmetric cell gaps is gradually changed,thereby improving the visibility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view showing a liquid crystal display according toan exemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1;

FIG. 3 is a cross-sectional view schematically illustrating a liquidcrystal display in which a cell gap is constantly formed in a panel;

FIG. 4 is a cross-sectional view schematically illustrating how theliquid crystal display of FIG. 3 is bent;

FIG. 5 is a cross-sectional view schematically illustrating a liquidcrystal arrangement of an entire panel in a liquid crystal displayaccording to an exemplary embodiment of the present disclosure;

FIG. 6 is a cross-sectional view schematically illustrating how theliquid crystal display of FIG. 5 is bent;

FIG. 7 is a top plan view showing a liquid crystal display according toan exemplary embodiment of the present disclosure;

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.7;

FIG. 9 is a cross-sectional view taken along the line IX-IX of FIG. 7from a central portion of a panel;

FIG. 10 is a cross-sectional view taken along the line IX-IX of FIG. 7from a peripheral portion of the panel;

FIGS. 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, andFIG. 26 are cross-sectional views showing a manufacturing method of aliquid crystal display according to an exemplary embodiment of thepresent disclosure; and

FIG. 27 is a cross-sectional view taken along the line II-II of FIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the present inventive concept willbe described in detail with reference to the accompanying drawings. Asthose skilled in the art would realize, the described embodiments may bemodified in various ways, all without departing from the spirit or scopeof the inventive concept. Exemplary embodiments introduced herein areprovided to make disclosed contents thorough and complete and tosufficiently transfer the spirit of the inventive concept to thoseskilled in the art.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. It will be understood that when a layer isreferred to as being “on” another layer or substrate, it can be directlyon the other layer or substrate, or intervening elements may also bepresent. Like reference numerals designate like elements throughout thespecification. A substrate may have a “central portion,” which is anarea near its center. Where the substrate will be bent to have acurvature along a first direction, the “central portion” includes anarea that is at or near the centerline extending perpendicularly to thefirst direction (see FIG. 1). “Peripheral portion” is intended toinclude the area outside the central portion including the area near theedges of the substrate.

FIG. 1 is a top plan view showing a liquid crystal display according toan exemplary embodiment of the present invention. FIG. 2 is across-sectional view taken along the line II-II of FIG. 1.

The liquid crystal display according to the present exemplary embodimentincludes a display area DA and a peripheral area PA positioned tosurround the display area DA.

The display region DA is a region where an actual image is outputted.The peripheral region PA has a gate driver or a data driver, or a gatepad portion (not shown), a data pad portion (not shown) including a gatepad, a data pad, or the like, which is a portion connected to anexternal circuit. The gate pad is a wide portion positioned at an end ofa gate line, and the data pad is a wide portion positioned at an end ofa data line.

A plurality of microcavities 305 are formed in the display area DA ofthe liquid crystal display according to the present exemplaryembodiment. The microcavities 305 serve as spaces for receiving a liquidcrystal material, thereby forming a liquid crystal layer. Themicrocavities 305 may be disposed on a thin film transistor array panel100 to correspond to the liquid crystal layer. The microcavities 305 arecovered with a roof layer 360. The thin film transistor array panel 100includes a thin film transistor, wires, and the like for driving theliquid crystal display.

As illustrated in FIG. 2, according to the present exemplary embodiment,a difference between the maximum and minimum cell gaps of themicrocavities 305 disposed at the peripheral portion of the panel or thethin film transistor array panel 100 is greater than a differencebetween the maximum and minimum cell gaps of the microcavities 305disposed at the central portion thereof. Specifically, the cell gap d1of the microcavities 305 disposed at two opposite ends of the centralportion of the thin film transistor array panel 100 is substantiallyconstant. On the other hand, microcavities 305 disposed at theperipheral portion of the thin film transistor array panel 100 each havecell gaps d1 and d2 that are different from each other. The differencebetween the maximum value and the minimum value of the cell gaps of themicrocavities 305 is gradually increased from the central portion to theperipheral portion of the thin film transistor array panel 100, suchthat there is a gradient of cell gap Δd between the central portion andthe peripheral portion. Since the maximum value and the minimum value ofthe cell gaps of the microcavities 305 disposed at the central portionare substantially the same, the difference between the maximum value andthe minimum value of the cell gaps may be in a range of 0 to adifference between a first cell gap d1 and a second cell gap d2.

In the present exemplary embodiment, a horizontal length of the thinfilm transistor array panel 100 may be larger than a vertical lengththereof. A forward direction from the central portion to the peripheralportion of the thin film transistor array panel 100 may be defined as afirst direction D1 that is parallel with horizontal long sides thereof,or a second direction D2 that is opposite to the first direction D1. Inthe direction of the long sides, the cell gaps of the microcavities 305disposed at the central portion of the thin film transistor array panel100 may be substantially the same.

The exemplary embodiment of FIG. 2 may be modified as illustrated inFIG. 27

Referring to FIG. 27, a mean value of the right/left cell gaps of themicrocavity 305 is substantially constant from the central portion tothe peripheral portion of the thin film transistor array panel 100, suchthat it is more advantageous in terms of luminance. In the presentexemplary embodiment, a mean value of the right/left cell gaps of themicrocavity 305 disposed at the central portion of the thin filmtransistor array panel 100 is substantially the same as a mean value ofthe right/left cell gaps of the microcavity 305 disposed at theperipheral portion thereof.

Hereinafter, arrangement of a liquid crystal material in a liquidcrystal display according to an exemplary embodiment of the presentinvention will be described with reference to FIG. 3 to FIG. 6 bycomparing it with the conventional case.

FIG. 3 is a cross-sectional view schematically illustrating a liquidcrystal display in which a cell gap is constantly formed in a panel.FIG. 4 is a cross-sectional view schematically illustrating how theliquid crystal display of FIG. 3 is bent. FIG. 5 is a cross-sectionalview schematically illustrating a liquid crystal arrangement of anentire panel in a liquid crystal display according to an exemplaryembodiment. FIG. 6 is a cross-sectional view schematically illustratinghow the liquid crystal display of FIG. 5 is bent.

For convenience of description, the cross-sectional views of FIG. 3 toFIG. 6 show one single microcavity 305 instead of the partitionedmicrocavities 305 corresponding to the entire display area of the liquidcrystal display, unlike in FIG. 2.

Referring to FIG. 3, when the cell gap is constant for the microcavities305 disposed at the central portion and the peripheral portion of thethin film transistor array panel 100, a liquid crystal material 310 issubstantially vertically aligned.

Referring to FIG. 4, when the liquid crystal display shown in FIG. 3 isbent to have a predetermined curvature radius (e.g., 600 R), the viewpoint of a viewer and an optical axis of the liquid crystal material arealigned with each other at the central portion of the thin filmtransistor array panel 100, while an angle is generated between the viewpoint of the viewer and the optical axis of the liquid crystal materialby the curvature at the peripheral portion of the thin film transistorarray panel 100. In FIG. 4, an angle of about 8 degrees is generatedbetween the view point and the optical axis of the liquid crystalmaterial at the peripheral portion. In this case, although it is assumedthat the cell gaps are not changed, a difference in light visibility maybe generated between the central portion and the peripheral portion ofthe thin film transistor array panel 100. For example, when a curvatureis applied in a black state in which no electric field is applied, alight leakage phenomenon may be generated due to a retardation effect atthe peripheral portion of the thin film transistor array panel 100,whereas such leakage is significantly less in the central portion.

This light visibility difference may cause a reduction in the degree ofradiation variation even in a white state when an electric field isapplied, thereby deteriorating the transmittance of the peripheralportion as compared with the central portion of the thin film transistorarray panel 100.

However, referring to FIG. 2 and FIG. 5, the difference Δd between themaximum value and the minimum value of the cell gaps within themicrocavity 305 is gradually increased as the position of themicrocavity 305 shifts from the central portion toward the peripheralportion of the liquid crystal display. In the present exemplaryembodiment, the roof layer 360 covering the microcavity 305 has athickness that is gradually increased from the central portion to theperipheral portion of the thin film transistor array panel 100. The rooflayer 360 has a bottom surface that is positioned to face themicrocavity 305 and a top surface that is positioned to correspond tothe bottom surface. In the present exemplary embodiment, the bottomsurface of the roof layer 360 may have a curvature, and the top surfacethereof may be parallel with the thin film transistor array panel 100.Accordingly, pretilt angles of the liquid crystal materials 310 disposedat an upper portion of the microcavity 305 and a lower portion thereofmay be different from each other. This pretilt angle difference betweenthe liquid crystal materials 310 disposed at the upper portion of themicrocavity 305 and the lower portion thereof may be gradually increasedfrom the central portion to the peripheral portion of the thin filmtransistor array panel 100. Herein, in the microcavity 305 disposed atthe peripheral portion, the liquid crystal material 310 that ispositioned to be adjacent to the thin film transistor array panel 100may be substantially vertically aligned, and the liquid crystal material310 that is positioned to be adjacent to the roof layer 360 may have atilt angle.

Referring to FIG. 6, when the liquid crystal display shown in FIG. 5 isbent to have a predetermined curvature radius (e.g., 600 R in thepresent exemplary embodiment), the liquid crystal material 310 that ispositioned to be adjacent to the roof layer 360 may be substantiallyvertically aligned, and the liquid crystal material 310 that ispositioned to be adjacent to the thin film transistor array panel 100may have a tilt angle in the microcavity 305 that is disposed to beadjacent to the peripheral portion of the thin film transistor arraypanel 100.

According to the liquid crystal continuous theory, the liquid crystalmaterial 310 may be aligned to have a tilt angle that is graduallyincreased from the upper portion to the lower portion of the microcavity305 disposed at the peripheral portion by a tilt angle differencebetween the upper portion and the lower portion of the microcavity 305.Accordingly, since the liquid crystal material 310 disposed at an upperportion of the peripheral portion of the liquid crystal displayaccording to the present exemplary embodiment is vertically aligned tobe substantially parallel to the view point, it is possible to minimizethe degree of retardation variation between the central portion and theperipheral portion of the thin film transistor array panel 100, therebyimproving visibility.

FIG. 7 is a top plan view showing a liquid crystal display according toan exemplary embodiment of the present disclosure. FIG. 8 is across-sectional view taken along the line VIII-VIII of FIG. 7. FIG. 9 isa cross-sectional view taken along the line IX-IX of FIG. 7 from acentral portion of a panel. FIG. 10 is a cross-sectional view takenalong the line IX-IX of FIG. 7 from a peripheral portion of the panel.FIG. 7 illustrates a 2×2 pixel portion A of a plurality of pixels thatare respectively disposed to correspond to the microcavities 305, andthis pixels may be repeatedly arranged up/down and right/left in theliquid crystal display according to the exemplary embodiment of thepresent disclosure.

Referring to FIG. 7 to FIG. 9, a gate line 121 and a storage electrodeline 131 are formed on a substrate 110 made of transparent glass orplastic. The gate line 121 includes a gate electrode 124. The storageelectrode line 131 mainly extends in a horizontal direction, andtransfers a predetermined voltage such as a common voltage Vcom. Thestorage electrode line 131 includes a pair of vertical storage electrodeportions 135 a substantially extending to be perpendicular to the gateline 121, and a horizontal storage electrode portion 135 b connectingends of the pair of vertical storage electrode portions 135 a to eachother. The vertical and horizontal storage electrode portions 135 a and135 b have a structure surrounding a pixel electrode 191.

A gate insulating layer 140 is formed on the gate line 121 and thestorage electrode line 131. A semiconductor layer 151 disposed under adata line 171 and a semiconductor layer 154 positioned under asource/drain electrode and corresponding to a channel region of a thinfilm transistor Q are formed on the gate insulating layer 140.

A plurality of ohmic contacts may be formed between the semiconductorlayer 151 and the data line 171, and between the semiconductor layer 154under the source/drain electrode and corresponding to the channel regionand the source/drain electrode, and are omitted in the drawings.

Data conductors 171, 173, and 175 including a source electrode 173, thedata line 171 connected to the source electrode 173, and a drainelectrode 175 are formed on the semiconductor layers 151 and 154 and thegate insulating layer 140.

The gate electrode 124, the source electrode 173, and the drainelectrode 175 form a thin film transistor Q along with the semiconductorlayer 154, and the channel of the thin film transistor Q is formed inthe exposed portion of the semiconductor layer between the sourceelectrode 173 and the drain electrode 175.

A first interlayer insulating layer 180 a is formed on the dataconductors 171, 173, and 175 and the exposed semiconductor layer 154.The first interlayer insulating layer 180 a may include an inorganicinsulator such as a silicon nitride (SiNx) and a silicon oxide (SiOx),or an organic insulator.

A color filter 230 and light blocking members 220 a and 220 b are formedon the first interlayer insulating layer 180 a.

First, the light blocking members 220 a and 220 b have a latticestructure having an opening corresponding to an area displaying animage, and are formed of a material though which no light can pass. Thecolor filter 230 is formed in each opening of the light blocking members220 a and 220 b. The light blocking members 220 a and 220 b include ahorizontal light blocking member 220 a formed in a direction parallelwith the gate line 121, and a vertical light blocking member 220 bformed in a direction parallel to the data line 171.

The color filter 230 may display one of three primary colors such asred, green, and blue. However, it is not limited to the three primarycolors such as red, green, and blue, and may display one of cyan,magenta, yellow, and white-based colors. The color filter 230 may beformed of materials displaying different colors for each adjacent pixel.

A second interlayer insulating layer 180 b covering the color filter 230and the light blocking members 220 a and 220 b is formed on the colorfilter 230 and the light blocking members 220 a and 220 b. The secondinterlayer insulating layer 180 b may include the inorganic insulatingmaterial, such as a silicon nitride (SiNx) and a silicon oxide (SiOx),or the organic insulating material.

In a case where a step is generated due to a difference in a thicknessbetween the color filter 230 and the light blocking members 220 a and220 b, the second interlayer insulating layer 180 b includes an organicinsulating material, so that it is possible to decrease or remove thestep.

The color filter 230, the light blocking members 220 a and 220 b, andthe interlayer insulating layers 180 a and 180 b have a contact hole 185exposing the drain electrode 175.

The pixel electrode 191 is disposed on the second interlayer insulatinglayer 180 b. The pixel electrode 191 may be formed of a transparentconductive material, such as ITO or IZO.

An overall shape of the pixel electrode 191 is a quadrangle, and thepixel electrode 191 includes cross stems configured by a horizontal stem191 a and a vertical stem 191 b crossing the horizontal stem 191 a.Further, the pixel electrode 191 is divided into four sub-regions by thehorizontal stem 191 a and the vertical stem 191 b, and each sub-regionincludes a plurality of minute branches 191 c. In the present exemplaryembodiment, the pixel electrode 191 may further include an outer stem191 d connecting the minute branches 191 c at right and left edges ofthe pixel electrode 191. In the present exemplary embodiment, the outerstem 191 d is positioned at the right and left edges of the pixelelectrode 191, however it may be positioned to extend to an upperportion or a lower portion of the pixel electrode 191.

The minute branches 191 c of the pixel electrode 191 form an angle ofapproximately 40° to 45° with the gate line 121 or the horizontal stem191 a. Further, the minute branches of two adjacent sub-regions may beperpendicular to each other. In addition, a width of each minute branchmay be gradually increased, or a distance between the minute branches191 c may be varied.

The pixel electrode 191 includes an extension 197 which is connected ata lower end of the vertical stem 191 b, has a larger area than thevertical stem 191 b, and is electrically and physically connected to thedrain electrode 175 through the contact hole 185 at the extension 197,thereby receiving the data voltage from the drain electrode 175.

The thin film transistor Q and the pixel electrode 191 described aboveare just examples, and a structure of the thin film transistor and adesign of the pixel electrode may be modified in order to improve sidevisibility.

A lower alignment layer 11 is formed on the pixel electrode 191, and maybe a vertical alignment layer. The lower alignment layer 11, as a liquidcrystal alignment layer made of a material such as polyamic acid, apolysiloxane, a polyimide, or the like, may include at least one ofgenerally used materials.

An upper alignment layer 21 is disposed at a portion facing the loweralignment layer 11, and a microcavity 305 is formed between the loweralignment layer 11 and the upper alignment layer 21. A liquid crystalmaterial including liquid crystal molecules 310 is injected into themicrocavity 305, and the microcavity 305 has an entrance region 307. Themicrocavities 305 may be formed along a column direction of the pixelelectrode 191, that is, in the vertical direction. In the presentexemplary embodiment, the alignment material forming the alignmentlayers 11 and 21 and the liquid crystal material including the liquidcrystal molecules 310 may be injected into the microcavity 305 by usingcapillary force. In the present exemplary embodiment, the loweralignment layer 11 and the upper alignment layer 21 are merelydistinguished according to position, and may be connected to each otheras shown in FIG. 4. The lower alignment layer 11 and the upper alignmentlayer 21 may be simultaneously formed.

The microcavity 305 is divided in the vertical direction by a pluralityof liquid crystal injection portion 307FP positioned at a portionoverlapping the gate line 121, thereby forming the plurality ofmicrocavities 305, and a plurality of microcavities 305 may be formedalong a column direction of the pixel electrode 191, that is, in thevertical direction. Further, the microcavity 305 is divided in thehorizontal direction by a partition PWP that will be described later,thereby forming a plurality of microcavities 305, and the microcavities305 may be formed along the row direction of the pixel electrode 191,that is, the horizontal direction in which the gate line 121 extends.The microcavities 305 may respectively correspond to one or more pixelareas, and the pixel areas may correspond to a region displaying theimage.

A common electrode 270 and a lower insulating layer 350 are positionedon the upper alignment layer 21. The common electrode 270 receives thecommon voltage, and generates an electric field together with the pixelelectrode 191 to which the data voltage is applied to determine adirection in which the liquid crystal molecules 310 positioned at themicrocavity 305 between the two electrodes are inclined. The commonelectrode 270 forms a capacitor with the pixel electrode 191 to maintainthe received voltage even after the thin film transistor is turned off.The lower insulating layer 350 may be formed of a silicon nitride (SiNx)or a silicon oxide (SiOx).

In the present exemplary embodiment, it is described that the commonelectrode 270 is formed on the microcavity 305, but in another exemplaryembodiment, the common electrode 270 is formed under the microcavity305, so that liquid crystal driving according to a coplanar electrode(CE) mode is possible.

The roof layer 360 is disposed on the lower insulating layer 350. Theroof layer 360 serves as a support so that the microcavity 305, which isa space between the pixel electrode 191 and the common electrode 270, isformed. The roof layer 360 may include silicon oxycarbide (SiOC), aphotoresist, or other organic materials. In the present exemplaryembodiment, the roof layer 360 of the center portion may be formed tohave substantially the same thickness in a horizontal direction.

An upper insulating layer 370 is disposed on the roof layer 360. Theupper insulating layer 370 may contact the upper surface of the rooflayer 360. The upper insulating layer 370 may be formed of a siliconnitride (SiNx) or a silicon oxide (SiOx). As shown in FIG. 8, the upperinsulating layer 370 may be disposed to cover the side surface of theroof layer 360.

In the present exemplary embodiment, a capping layer 390 is alsodisposed at the liquid crystal injection portion 307FP and the entranceregion 307 of the microcavity 305 exposed by the liquid crystalinjection portion 307FP. The capping layer 390 includes the organicmaterial or the inorganic material.

As shown in FIG. 9, in the present exemplary embodiment, the partitionPWP is formed between horizontally neighboring microcavities 305. Thepartition PWP may extend along the data line 171, and may be covered bythe capping layer 390. The lower insulating layer 350, the commonelectrode 270, the upper insulating layer 370, and the roof layer 360are filled in the partition PWP, and this structure forms the partitionwall to partition or define the microcavity 305. In the presentexemplary embodiment, a partition structure such as the partition PWP isdisposed between the microcavities 305. Accordingly, even though thesubstrate 110 is bent, less stress may be generated and a degree atwhich the cell gap is deformed may be reduced.

The structure of the peripheral portion shown in FIG. 10 is mostlysimilar to the structure of the central portion shown in FIG. 9, but thecell gaps d1 and d2 of the microcavity 305 disposed at the peripheralportion are different. A left side of the cross-section shown in FIG. 10is positioned farther from the central portion of the substrate 110. Thethickness of the roof layer 360 disposed to correspond to themicrocavity 305 disposed at the peripheral portion may be increased at aposition that is more separated from the central portion. In this case,the first cell gap d1 may be the same as the cell gap d1 of the centralportion, and a minimum value d3 of cell gaps of a microcavity that isrightwardly adjacent to the microcavity 305 having the maximum value ofthe first cell gap d1 and the minimum value of the second cell gap d2may be greater than the second cell gap d2.

Next, an exemplary embodiment for a manufacturing method of theabove-described liquid crystal display will be described with referenceto FIG. 11 to FIG. 26. An exemplary embodiment to be described below maybe varied as an exemplary embodiment of the manufacturing method.

FIG. 11 to FIG. 26 are cross-sectional views showing a manufacturingmethod of a liquid crystal display according to an exemplary embodimentof the present invention. FIGS. 11, 14, 17, 20, 21, and 24 sequentiallyillustrate cross-sectional views taken along the line VIII-VIII of FIG.7. FIGS. 12, 15, 18, 22, and 25 sequentially illustrate cross-sectionalviews taken along the line IX-IX of FIG. 7 from a central portion of apanel. FIGS. 13, 16, 19, 23, and 26 sequentially illustratecross-sectional views taken along the line IX-IX of FIG. 7 from aperipheral portion of the panel.

Referring to FIG. 7, FIG. 11, and FIG. 12, to form a generally knownswitching element on a substrate 110, a gate line 121 extending in ahorizontal direction and a gate insulating layer 140 on the gate line121 are formed, semiconductor layers 151 and 154 are formed on the gateinsulating layer 140, and a source electrode 173 and a drain electrode175 are formed. In this case, the data line 171 connected to the sourceelectrode 173 may be formed to extend in a vertical direction whilecrossing the gate line 121.

The first interlayer insulating layer 180 a is formed on the dataconductors 171, 173, and 175 including the source electrode 173, thedrain electrode 175, and the data line 171, and the exposed portion ofthe semiconductor layer 154.

The color filter 230 is formed at a position corresponding to the pixelarea on the first interlayer insulating layer 180 a, and the lightblocking members 220 a and 220 b are formed between the color filters230. When the light blocking members 220 a and 220 b are formed, thelight blocking layer 221 disposed at the peripheral portion may also beformed together with them.

The second interlayer insulating layer 180 b is formed to cover thecolor filter 230 and the light blocking members 220 a and 220 b, and thesecond interlayer insulating layer 180 b is formed to have the contacthole 185 electrically and physically connecting the pixel electrode 191and the drain electrode 175.

Thereafter, the pixel electrode 191 is formed on the second interlayerinsulating layer 180 b, and a sacrificial layer 300 is formed on thepixel electrode 191. As illustrated in FIG. 12, an open portion OPN isformed in the sacrificial layer 300 in a direction parallel with thedata line 171. In a subsequent process, the common electrode 270, thelower insulating layer 350, the roof layer 360, and the upper insulatinglayer 370 are filled in the open portion OPN to form the partition wallformation portion PWP.

Referring to FIG. 13, in a first sacrificial layer pattern 300-1disposed at the peripheral portion, a height difference between themaximum value d1 and the minimum value d2 at two ends of the firstsacrificial layer 300-1 is increased at a position farther away from thecentral portion of the panel. A left side of the cross-section shown inFIG. 13 is farther from the central portion of the substrate 110 thanthe right side of FIG. 13. The sacrificial layer pattern 300 (whichcollectively refers to 300-1, 300-2, etc.) may indicate sacrificiallayer patterns 300-1, 300-2, etc. corresponding to each microcavity 305.The thickness of the sacrificial layer pattern 300-1 disposed at theperipheral portion may be reduced at a position that is farther from thecentral portion. In the embodiment of FIG. 13, the first thickness d1may be the same as the thickness of the sacrificial layer pattern 300-idisposed at the central portion. A minimum value d3 of a third thicknessof a sacrificial layer pattern 300-2 that is between the sacrificiallayer pattern 300-1 and the central sacrificial layer pattern 300-i, mayhave the maximum value of the first thickness d1 and the minimum valueof the second thickness d2. In one embodiment, the value d3 of thesacrificial layer 300-s may be greater than the second thickness d2. Aslit mask may be employed to form the sacrificial layer pattern 300.This slit mask may have a structure for gradually changing the opticaltransmittance at portions corresponding to each microcavity beingfarther from the central portion of the panel.

Referring to FIG. 14 and FIG. 16, the common electrode 270, the lowerinsulating layer 350, and the roof layer 360 are sequentially formed onthe sacrificial layer 300. In FIG. 14 and FIG. 16, the central portionof the panel is to the right of the portion that is depicted. The rooflayer 360 may be removed at the region corresponding to the horizontallight blocking member 220 a disposed between the pixel areas adjacent inthe vertical direction by an exposure and development process. The rooflayer 360 exposes the lower insulating layer 350 in the regioncorresponding to the horizontal light blocking member 220 a. In thiscase, the common electrode 270, the lower insulating layer 350, and theroof layer 360, as shown in FIG. 15 and FIG. 16, fill the open portionOPN of the vertical light blocking member 220 b, thereby forming thepartition forming portion PWP. As shown in FIG. 16, a thickness of aportion of the roof layer 360 to correspond to the sacrificial layerpattern 300 disposed at the peripheral portion of the panel may increasewith distance from the central portion of the panel.

Referring to FIG. 17 to FIG. 19, the upper insulating layer 370 isformed in such a way so as to cover upper portions of the roof layer 360and the exposed lower insulating layer 350.

Referring to FIG. 20, the upper insulating layer 370, the lowerinsulating layer 350, and the common electrode 270 are etched topartially remove the upper insulating layer 370, the lower insulatinglayer 350, and the common electrode 270, and to form the liquid crystalinjection portion 307FP. In this case, the upper insulating layer 370has a structure covering the side surface of the color filter 230;however, this is not a limitation of the disclosure, and the upperinsulating layer 370 covering the side surface of the color filter 230may be removed to expose the side surface of the color filter 230 to theoutside.

Referring to FIG. 21 to FIG. 23, the sacrificial layer pattern 300 isremoved by an oxygen (O₂) ashing process or a wet-etching method throughthe liquid crystal injection portion 307FP. In this case, themicrocavity 305 having the entrance region 307 is formed. Themicrocavity 305 is an empty space formed when the sacrificial layer 300is removed.

Referring to FIG. 24 to FIG. 26, the alignment material is injectedthrough the entrance region 307 to form the alignment layers 11 and 21on the pixel electrode 191 and the common electrode 270. In detail, abake process is performed after injecting an alignment materialincluding a solid content and a solvent through the entrance region 307.

Next, a liquid crystal material including the liquid crystal molecules310 is injected into the microcavity 305 via the entrance region 307,using an inkjet method and the like.

Thereafter, the capping layer 390 is formed on the insulating layer 350to cover the entrance region 307 and the liquid crystal injectionportion 307FP to form the liquid crystal display illustrated in FIG. 7to FIG. 10.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

<Description of Symbols> 300 sacrificial layer 305 microcavities 307entrance region 307FP liquid crystal injection portion 350 lowerinsulating layer 360 roof layer 370 upper insulating layer 390 cappinglayer

What is claimed is:
 1. A liquid crystal display comprising: a substratehaving a central portion; a thin film transistor disposed on thesubstrate; a pixel electrode connected to the thin film transistor; aroof layer disposed to face the pixel electrode; and a liquid crystallayer disposed between the pixel electrode and the roof layer and formedby a plurality of microcavities, wherein the microcavities hold a liquidcrystal material, wherein a difference between a maximum cell gap and aminimum cell gap in each of the microcavities increases with distancefrom the central portion of the substrate.
 2. The liquid crystal displayof claim 1, wherein a pretilt angle of the liquid crystal materialdisposed at an upper portion of one of the microcavities is differentfrom that of the liquid crystal material disposed at a lower portion ofthe same one of the microcavities.
 3. The liquid crystal display ofclaim 2, wherein a pretilt angle difference between the liquid crystalmaterials disposed at the upper portion and the lower portion of themicrocavities increases from the central portion to the peripheralportion.
 4. The liquid crystal display of claim 3, wherein the rooflayer has a curved bottom surface that interfaces the microcavities anda flat top surface that is parallel with the substrate.
 5. The liquidcrystal display of claim 3 wherein the substrate is bent, wherein abottom surface of the roof layer is parallel with the substrate and atop surface of the roof layer has a curvature.
 6. The liquid crystaldisplay of claim 4 wherein, at one of the microcavities in theperipheral portion, the liquid crystal material that is adjacent to thesubstrate is substantially vertically aligned to the substrate and theliquid crystal material that is adjacent to the roof layer has a tiltangle.
 7. The liquid crystal display of claim 3 wherein the substrate isbent, wherein the liquid crystal material that is adjacent to the rooflayer is substantially vertically aligned and the liquid crystalmaterial that is adjacent to the substrate has a tilt angle in themicrocavities disposed at the peripheral portion.
 8. The liquid crystaldisplay of claim 1, wherein a difference between a maximum thickness anda minimum thickness of the roof layer increases with distance from thecentral portion of the substrate.
 9. The liquid crystal display of claim1 wherein the substrate is bent, wherein a thickness of the roof layeris constant across the substrate.
 10. The liquid crystal display ofclaim 1, wherein a forward direction from the central portion to theperipheral portion is substantially parallel with long sides of thesubstrate.
 11. The liquid crystal display of claim 10, wherein cell gapsof the microcavities disposed in the central portion of the substrateare substantially constant.
 12. The liquid crystal display of claim 1,wherein a tilt angle of the liquid crystal material that is adjacent tothe roof layer at the microcavities increases with distance from thecentral portion of the substrate.
 13. A manufacturing method of a liquidcrystal display, the method comprising: forming a thin film transistoron a substrate; forming a pixel electrode to be connected to the thinfilm transistor; forming sacrificial layer patterns on the pixelelectrode; forming a roof layer on the sacrificial layer patterns;forming a plurality of microcavities by removing the sacrificial layerpatterns; forming a liquid crystal layer by injecting a liquid crystalmaterial into the microcavities; and forming a capping layer on the rooflayer, wherein, in the forming of the sacrificial layer patterns, adifference between a maximum height and a minimum height of each of aplurality of sacrificial layer patterns increases with distance from acentral portion of the substrate.
 14. The manufacturing method of claim13, further comprising using a slit mask to form the sacrificial layerpatterns.
 15. The manufacturing method of claim 14, wherein the rooflayer has a curved bottom surface interfacing the microcavities and aflat top surface that is parallel with the substrate.
 16. Themanufacturing method of claim 15, further comprising bending thesubstrate such that the bottom surface of the roof layer is parallelwith the substrate and the top surface has a curvature.
 17. Themanufacturing method of claim 13, wherein a difference between a maximumthickness and a minimum thickness of the roof layer increases withdistance from the central portion of the substrate.
 18. Themanufacturing method of claim 17, further comprising bending thesubstrate such that a thickness of the roof layer is constant.
 19. Themanufacturing method of claim 13, wherein a forward direction from thecentral portion to the peripheral portion is parallel with long sides ofthe substrate.
 20. The manufacturing method of claim 19, wherein cellgaps of the microcavities disposed at the central portion of thesubstrate are substantially constant.